@ARTICLE{Ebrahimi, author = {Rahmat, Neda and Ebrahimi, Saeed and Mazidi, Abbas and }, title = {Nonlinear vibrations modeling and sensitivity analysis of the coupled roll and heave motions of a ship}, volume = {15}, number = {12}, abstract ={In recent decades, study of the behavior of ship motion in waves is considered by researchers. In this paper, mathematical modeling of nonlinear coupling of roll and heave modes of a ship under harmonic excitation in heave direction is studied. The method of multiple scales is used to solve nonlinear equations. Equations of motion in harmonic excitation is studied. In order to validate the responses obtained by the method of multiple scales, the response obtained for a sample is compared with the numerical solution of the equation and good agreement is obtained. Analysis ship motion requires time consuming computations in large scaled model. In addition to evalution of nonlinear coupling roll motion with heave in forced vibrations, the motion is modeled with a simple mechanical system includes mass–spring-damper and pendulum under identical conditions and the response of equal system with response of the original system is consistent. Sensitivity analysis was carried out for nonlinear coupling of roll and heave in harmonic excitation with local and partial derivative methods and the results from two methods is compared. }, URL = {http://mme.modares.ac.ir/article-15-9829-en.html}, eprint = {http://mme.modares.ac.ir/article-15-9829-en.pdf}, journal = {Modares Mechanical Engineering}, doi = {}, year = {2016} }